Low
C (Flashing) on Halstead Ace HE

Your boiler has been manually or accidentally switched into a service testing mode, meaning it is running at a restricted low power level rather than responding to your heating demands.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

The appliance enters the SERVICE mode (runs at minimum CH output).

From this model's manual
Verified against the AceHE_installation installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Locate the selector switch on the front control panel.Ensure the switch is set to the 'Off/Reset' position for a few seconds.Turn the switch back to the 'Heating and Hot Water' position to exit the service mode.

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